Frequently, packers need to be set in wellbores, but access below them is also necessary to allow other downhole components to be actuated by hydraulic pressure through a control line, or by electronic means through an I-wire. I-wire is defined to encompass a cable of any type, including fiber optic, or conductor which conducts power or signals between the surface and downhole and any points in between.
Prior designs have made provisions for such needs through the mandrel of the packer. Thus, for example, to allow a control line to pass through the packer body, the mandrel had connections above and below. The control line would be assembled with the string and connected to the underside of the packer mandrel. Thereafter, another connection would be put in the upper end of the packer mandrel and the control line would be continued with the tubing string so that it would eventually reach the surface. A pressure source would then be connected to the control line at the surface to allow for actuation of the downhole components hydraulically. This procedure could be repeated if multiple control lines were to be used.
Wires or cables could be run through the mandrel body in a similar manner. The wire required a terminal connection above and below the packer mandrel to seal around the periphery of the cable, or the packer mandrel body itself could be prewired from the top and bottom connections. In this manner, leakage through the mandrel body was avoided by using the sealed electrical connections at the top and bottom of the mandrel body.
Both these techniques for running control line or I-wire through the mandrel body had undesirable aspects. The most prevalent undesirable aspect of the prior technique was the addition of joints. With the control line, the additional joints present a potential leak path which, if sufficiently severe, would undermine the operation of the downhole components relying upon pressurization in the control line. Similarly, with the I-wire, the necessity of connections above and below the packer posed potential problems not only from a leakage point of view, but also from a reliability aspect with regard to the circuits being jeopardized by infiltration of wellbore fluids. Accordingly, an object of the present invention is to facilitate the running of I-wires or control lines around a packer in a manner where additional joints are not required, thus avoiding the potential problems of the prior techniques. These and other objectives of the present invention will be better understood by a review of the description of the preferred embodiment below.